Microsoft has done something that might surprise a bunch of people out there, it has open sourced the WSL (Windows Subsystem for Linux) to make it easier for Windows users to run Linux distributions. The WSL sample that is now open source allows distro maintainers to build WSL packages for the Microsoft Store and to create custom Linux distro packages for sideloading. The distro launcher repo is on GitHub right now.

Microsoft says that the open source WSL will enable:

Linux distribution maintainers to package and submit a Linux distribution as an appx that runs on WSL

Developers to create custom Linux distributions that can be sideloaded onto their dev machine

Microsoft notes that since many Linux distros rely on open source software that it wanted to bring WSL closer to the OSS community. Microsoft wrote, "First, a little background on how we distribute Linux distros for WSL. We distribute Linux distros for WSL as UWP applications through the Microsoft Store. You can install those applications that will then run on WSL - the subsystem that sits in the Windows kernel. This delivery mechanism has many benefits as discussed in an earlier blog post."

Users who want to create a custom Linux distro package as an app to sideload on their own personal computer will not have their package distributed via the Microsoft Store. To get the custom distro on the Microsoft Store, the user would have to submit it as a distribution manager. Submitting to the store also requires the distro maintainer to work with Microsoft to get publishing approval.

If you are unfamiliar with what WSL is, it is intended to allow full Linux development for testing production code on a Windows machine. WSL allows the user to run Linux shell tools and open source languages along with Apache and MySQL. WSL doesn't support Linux graphical user interfaces; it is only meant to be an alternative to command-line interfaces.